That this House supports the maintenance of European Union citizenship rights for Welsh, Scottish, Northern Irish and English citizens; notes that the range of rights and protections afforded to individuals as European Union citizens are integral to a person’s European identity; further notes that many of those rights are closely linked to the UK’s membership of the Single Market; and calls on the UK Government to ensure that the UK’s membership of the Single Market and UK citizens’ right to European Union citizenship are retained in the event that the UK leaves the EU.

Before I begin, may I apologise to the House? I have a very bad head cold that has rendered me slightly deaf, although that is perhaps no great disadvantage in this place. I caution any Member who intervenes that I might have some difficulty hearing them.

Our motion calls for UK nationals to retain European citizenship after we leave the European Union. The key word here is “retain”: we wish to retain what we already have. It is supported by a wide range of organisations and individuals: the Scottish National party, the Liberal Democrats, the Green party, Open Britain, Best for Britain, the European Movement, The New European, Cymru Dros Ewrop—Wales for Europe, New Europeans, Our Future Our Choice, Brand EU, UKtoStay.EU and Another Europe is Possible, as well as Jo Maugham, QC, of the Good Law Project, and Professor Volker Roeben and Dr Pedro Telles, two of the authors of a report on EU citizenship commissioned by my good friend Jill Evans, the Plaid CymruMEP. Since the referendum, they have been arguing consistently for the retention of EU citizenship, and I recommend the report to anyone who wishes to pursue this argument. To the relief of hard-pressed Members, I can say that the executive summary is very good.

The crux of our argument is that although we are leaving the EU, the European citizenship rights conferred on UK citizens are not extinguished. Although we are leaving, those rights persist. Continuing Union citizenship is the more convincing interpretation of European and international law. Indeed, the principle that although a treaty might be bought to an end, the rights conferred by it are not extinguished, is enshrined strongly in international law. I refer Members to the 1969 Vienna convention on the law of treaties, which will be binding on member states, the UK and the EU itself post Brexit. Article 70(1)(b) of that convention provides that “legal situations” created during the currency of the treaties continue after withdrawal.

As Professor Roeben et al say on page five of the report:

“This interpretation of the Convention, that ongoing situations and rights continue, is supported by the overriding objective of ensuring legal certainty and preventing withdrawals from treaties having any retroactive effect. It is also supported by state practice.”

That is a crucial aspect of international law. Governments withdrawing from treaties cannot just abandon the rights their citizens already have. Professor Roeben tells me, by the way, that this article, as with much international law, was drawn up with the prominent participation of British legal experts.

There is an alternative reading that article 50 extinguishes all rights of the individual created by the founding treaties. In that case, both EU and international law would demand that a treaty be negotiated on associate Union citizenship, bringing with it a bundle of rights that might be little different from those that come with full citizenship. One way or other, we believe that EU citizenship of a sort is required.

The EU could legislate on citizenship post Brexit. That legislation would protect UK nationals in the EU, but would have no binding effect on the UK—by definition, because we would have left. We therefore urge the Government to look to achieving continuity and associate citizenship through the withdrawal agreement. That is why today’s debate is particularly timely.

The report concludes that neither continuity nor associate citizenship would require any revision of the founding treaties. There is a great deal more detail in the report that I will not go into today, but it will become pertinent if the Government recognise the force of our argument and proceed as we recommend. For now, I wish to set the context for our party’s position and say plainly from the start that Plaid Cymru campaigned to stay in the European Union. This was consistent with our long-term pro-European policy—indeed, that has been our policy since our establishment in 1925.

We have always been aware of our European history and our nation’s European heritage and have set great store by it. That has influenced our party profoundly. Our long-time president, Gwynfor Evans, who was the Member for Carmarthen, would rarely miss the opportunity to remind the people of Wales of our European heritage and our 1,500-year history as a people with our own language and culture, from our immediate post-Roman beginnings onwards to the present day. In fact, his conference speeches would often consist of retelling our history. I am reminded of a small joke made by two valleys members during one of Gwynfor’s speeches. One said to the other, “Good God, this is 20 minutes in and we are only in the 9th century!”